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This thesis describes the seasonality of the mesozooplankton community in Ramfjord, a shallow high-latitude fjord, in terms of diversity and behavior, using a combination of new and traditional methods. The approach aimed to gain insight into how environmental drivers such as photoperiod and food availability shape seasonal changes in mesozooplankton community structure and Calanus spp. behavior. Seasonal changes in diel vertical migration (DVM) were closely linked to the seasonal changes in day length. Monthly sampling over an entire annual cycle revealed that Ramfjord has particular characteristics such as the dominance of small copepods year-round in terms of abundance and biomass and a population of Calanus finmarchicus that enters a winter resting state rather than a diapause stage. This investigation also used metabarcoding as a quantitative tool for the first time, demonstrating the usefulness of this method in establishing the mesozooplankton community structure. Monthly monitoring of Calanus spp. swimming activity with the locomotor activity method confirmed the efficiency of this method in detecting overwintering in the Calanus population and determined that swimming activity can be used as a proxy for DVM behavior. This thesis demonstrates that the combination of newly developed methods (locomotor activity monitor and metabarcoding as a quantitative tool) with more traditional methods, such as visual identification and active acoustics, can provide new understanding of seasonal changes in the mesozooplankton community structure and behavior.

Small copepods (≤ 2 mm) are highly abundant mesozooplankton in Arctic and sub-Arctic marine ecosystems. However, small copepods are generally underestimated in zooplankton studies because of the use of large-meshed nets (≥ 180-µm mesh size) and are relatively poorly studied compared to large copepods. This thesis investigates the egg hatching rates, population dynamics and production rates of three abundant small copepod species in high-latitude ecosystems: Oithona similis, Microsetella norvegica, and Microcalanus pusillus. The egg hatching rates were investigated at between 1.3°C and 13.2°C by incubating ovigerous females. Field work was conducted in three sub-Arctic fjords and around Svalbard to obtain the biomass, age structure, and production of the populations sampled with a 64-µm mesh net. The egg hatching rates had various species-specific temperature response, which suggested different thermal plasticity among the three similar-sized species. The population dynamics of the three studied species also showed different patterns. M. norvegica has a time-limited reproduction resulting in a short but intense reproductive season and overwintering as adults. In contrast, O. similis and M. pusillus have continuous reproduction, where winter is used as recruitment period for a second generation. The most important findings of this thesis is the high biomass and production revealed by the quantitative sampling of small copepods. The biomass and production of small copepods could be equal to or even higher than that of large copepods, regardless of the season but with large spatial and interannual variations. In Balsfjord, the total production of the three small copepods could equal 0.3 to 27% of the primary production, meaning that small copepods have a significant role in the food web and carbon cycling of high-latitude ecosystems.

This thesis examines efficiency in the retail industry in two different directions. In the first setting, the link between inventory efficiency and performance is examined in relation to firm characteristics and exogenous explanatory variables. More specifically, in addition to general firm-specific characteristics, the effects of chain affiliation and time trends within retail chains is examined. The effects of business environment factors on inventory turnover are examined on the basis of geographic location and market conditions. In the customer efficiency setting, efficiency is studied by observing customers’ in-store behaviours to identify how specific customer characteristics in general, and the use of in-store carrying equipment in particular, are associated with shopper efficiency. These two avenues for detecting important retail efficiency metrics are examined in three individual research papers. The papers empirically demonstrate two different perspectives on efficiency that are important for retailers to be aware of. From this customer and retailer perspective, several dilemmas exist that have been only partly covered in the three papers. This dissertation aims to discuss some of these dilemmas and to demonstrate some of the dualities that exist in the intricate interconnection between the customer and the retailer in the pursuit of efficiency. Overall, the thesis offers new insights, makes significant contributions to the literature and to retail practice in terms of the complex topic of retailer logistical performance and customer efficiency and develops a better understanding of some tenets of eminent and sustainable brick and mortar retailing.

We focused on the responses of two arms of the Atlantic salmon immune system against intracellular pathogens: the antibody (Ab) production by B cells after challenge with the facultative intracellular bacterium Pisciricketsia salmonis and the interferon (IFN) responses in a salmonid cell line against salmon alphavirus (SAV), infectious necrotic pancreas virus (IPNV), and P. salmonis. We developed tools and generated knowledge on these immune responses to contribute to the development of effective vaccines against intracellular pathogens, focusing on P. salmonis. We induced CRISPR-Cas knock outs (KOs) in the salmonid cell line CHSE-214 for IRF3, IRF7, and MAVS. The induction of IFN responses was disrupted in the IRF3 and MAVS KOs, while we did not observe effects of similar magnitude in the IRF7 KO. Although replication of SAV was positively affected in the KOs with disrupted IFN induction, IPNV replication and P. salmonis growth were negatively affected by these KOs. To investigate Ab production after P. salmonis infection of Atlantic salmon, we developed two intraperitoneal challenge models. In the first study, we observed a significant increase in anti-P. salmonis serum Abs at 14 weeks post challenge (wpc), but not at 18 wpc. The fish were protected against a secondary challenge at 14 wpc, while the protection might have been reduced at 18 wpc. In the second in vivo study, we investigated the origin and specificity of early Ab responses using ELISpot and ELISA assays. The intraperitoneal challenge resulted in a major increase of leukocytes, total IgM Ab secreting cells (ASC), and anti-P. salmonis ASC in the peritoneal cavity (PerC), compared to the head kidney and spleen. Furthermore, we observed an early increase of non-specific Ab production, while specific Abs dominated the later time point. We discuss how our findings fit together in a model of specific and non-specific activation of B cells through B cell receptors and pattern recognition receptors, respectively, which could explain the early presence of non-specific Abs. Our model addresses the location of early Ab production, the transition to a more specific Ab response, and the possible functions of the PerC and its adipose tissue in this. Finally, we address the duration of Ab responses against P. salmonis, how our findings can contribute to the development of vaccine strategies with long term protection, and possible avenues for future research.

Planktonic early life stages of marine benthic invertebrates play an important role in dispersal and at times represent a substantial proportion of the zooplankton. Information about the larval communities present on the Arctic inflow shelves of the Barents and Chukchi Seas, however, is incomplete and limited because of infrequent sampling and low resolution of identification. The aims of the work described in this thesis were to characterize the meroplanktonic communities of the Barents and Chukchi Sea shelves in greater taxonomic (using DNA barcoding), spatial and temporal resolution than previously achieved, and to investigate the possible origins of the identified larvae. Key findings from this thesis include 1) much higher diversity of invertebrate larvae was found on the Arctic inflow shelves than previously, 2) larvae are present on the shelves year-round but their abundances peak in late summer and fall, 3) the larval community is composed mainly of taxa known to the region but there is evidence of some species drifting in from further south. Findings from this thesis highlight the immense potential gained from species-level identification and shine a light on critical yet poorly-known life stages of the rich Arctic shelf benthic communities in a time of rapid climate change.

Climate change is a major concern in the Arctic region, as large amounts of organic carbon (C) are stored in permafrost soils and sediments. Increasing average temperatures have the potential to release that C and making it available to biologic activity. Carbon-rich, anoxic soils such as peatlands are inhabited by methanogenic archaea that can metabolize by-products of microbial C decomposition and consequently release methane (CH4). Methane oxidizing bacteria (MOB) comprise a major biological filter for CH4 in terrestrial and aquatic ecosystems and thereby regulate CH4 emissions to the atmosphere. The genus Methylobacter has been detected in many CH4 rich ecosystems and several circumpolar locations. Climate change in the Arctic includes changes in both temperature and precipitation as well as ecosystem changes related to plant cover and herbivory. All of these changes have the potential to influence soil structure and soil biological processes. Thus, they are important factors controlling the soil C cycle and eventually the activity of MOB. The aim of this thesis was to investigate the ability of the Arctic biological CH4 filter to adapt to changes in vegetation, CH4 concentrations and temperature. Further, to gain insights in the resilience and resistance of the MOB community to environmental changes. We have shown that herbivory by geese changes the soil structure and thus the vertical distribution of CH4 and oxygen (O2) concentrations in a high Arctic peatland. These differences are accompanied by changes in the potential rates of CH4 oxidation. The highest activity was detected in shallower parts of the peatland in grazed sites compared to sites protected from grazing. Different MOB communities are responsible for the CH4 oxidation, depending on the above ground grazing and these communities are composed of closely related Methylobacter OTUs. Exposing peat soils from both grazed and protected sites to increased CH4 concentrations and temperature revealed that MOB respond strongly to changing CH4 concentrations, but apparently not to temperature. The response to changing CH4 concentrations involved different members of the Methylobacter community depending on the CH4 concentration and their previous exposure to herbivory. Temperature had minor effects on the CH4 oxidation activity and the MOB community pmoA transcription in the soils. However, temperature clearly influences growth, CH4 oxidation and CO2 production in the native peat soil isolate Methylobacter tundripaludum SV96. The temperature adaptation of M. tundripaludum SV96 is modulated by fine tuning transcription and translation to achieve the optimal balance between substrate availability, growth, and energy generation at different temperatures. These findings show that identical CH4 oxidation rates can be produced from very different physiological states. This also explains how the apparent lack of temperature responses in soil MOB communities is a result of physiological acclimation. Our results show that MOB in high Arctic peatlands and particular the genus Methylobacter is both physiologically and ecologically flexible in adapting to changes in plant cover, O2 distribution, CH4 concentrations and temperature. Thus, the MOB community comprises an efficient and resilient CH4 filter in high Arctic peat soils.

The rise in frequency of antibiotic resistant pathogenic bacteria makes the need for new treatment options for previously curable bacterial infections ever more important. In the process of discovering and developing antibacterial agents, one powerful approach has been borrowing wisdom from nature. Antimicrobial peptides (AMPs) are critical components of the innate immune systems found in almost all eukaryotic life forms. Their mode of action includes disruption of the bacterial membrane and to trigger supporting immune responses. Due to these properties, AMPs are considered promising lead structures that can be further developed into commercially available antibiotics to treat or prevent human diseases caused by bacteria. The work conducted in this thesis aims to discover and characterize novel antimicrobial peptides from the Arctic marine ascidian Synoicum turgens by using a marine bioprospecting approach. This includes collection, extraction and fractionation of biomass, antibacterial bioactivity testing and AMP isolation followed by chemical and biological characterization. For one isolated peptide class, truncated versions were prepared, aiming to produce shorter, linear variants with retained antimicrobial activity. In paper I, turgencin A and B and their oxidized derivatives were discovered through bioassay-guided purification. These peptides had an unusual disulfide connectivity, rarely seen in marine AMPs. Both turgencin A and B were potently active against all assayed bacterial strains. Membrane assays showed that the peptides cause bacterial membrane disruption within a few seconds. Turgencin A and B also displayed some cytotoxic activity against two human cell lines. Oxidation of the methionine present in both peptides decreased the bioactivities in all assays. Turgencin A, being the most potent AMP, was subject for sequence analysis and prediction of antimicrobial potential of different regions in paper II. Truncated and modified variants of turgencin A were synthetically produced to make smaller AMPs with the potential of being developed into antimicrobial drug leads. These 10-mer peptides, named StAMP-1–11, were made using an amino acid replacement strategy. Some of the Trp enriched peptides had similar bactericidal activity as the parent peptide turgencin A, and no cytotoxic activity against the mammalian cell lines. During turgencin isolation, a series of other smaller peptides were discovered in the same extracts presumably with antimicrobial activity. These isolated and characterized ~2 kDa, cysteine-rich peptides (CRPs) (described in paper III), were named St-CRP-1 and St-CRP-2 and contained 18-19 amino acids. The St-CRPs shared a disulfide connectivity pattern with alpha-defensins, had a neutral net charge, moderate antibacterial activity and showed no cytotoxicity. In addition, the introduction section provides background information on topics related to the thematic of the articles. This includes an introduction to bacteria, antibiotics and antibiotic resistance, AMPs, ascidians, and the marine environment.

Regarding the growing population and escalated development on the coasts, the environmental policymakers often face the dilemma of exploiting or protecting marine and coastal ecosystem services (ES). Therefore, the non-market valuation has become an essential instrument for supporting policymakers in eliciting preferences and welfare estimates regarding various ES, which further feed into the cost-benefit analyses (CBA). Among various non-market valuation techniques, the discrete choice experiment (DCE) methodology has gained ground in recent years for its advantages for capturing several trade- offs across multiple policy scenario alternatives and attributes. This thesis examines methodological issues regarding DCE applications on marine and coastal ES valuation and the further utilization of obtained non-market values in bio-economic models. Across three research papers utilizing DCE data collected in Arctic Norway, the results present implications for non-market valuation research and policymakers. The first paper studies the impact of including a socio-economic attribute in environmental policy DCE studies on the attendance paid to the other attributes. We utilize split sample DCE data to elicit preferences regarding coastal development on the Arctic coast, where we present an additional socio-economic attribute indicating the number of jobs created in the region in one version. The analysis suggests that a socio-economic attribute does not significantly alter the attention dedicated to other attributes. However, the obtained willingness-to-pay (WTP) measures significantly fluctuate across two samples, which can have important implications for the subsequent CBA. The second paper focuses on choice architecture interventions in DCE design. The study employs a three-way split sample for studying value activation through environmental and socio-economic signposts. Employing the case of coastal cod regulations and the controversial expansion of fishing tourism in Arctic Norway, the base DCE involves the attributes of coastal cod spawning stock biomass (SSB), stricter regulated user group, and cost. However, the other two versions include additional attributes of catch by fishing tourists (Treatment 1) and jobs created by fishing tourism (Treatment 2), which serve as decision signposts for value activation. The results indicate rather weak evidence for activating pre-existing pro-environmental and pro- development values through the adoption of signposts in DCE design. Nonetheless, we observe statistically significant differences in WTPs, supporting the results obtained in paper I. Finally, the third paper expands the standard bioeconomic models to incorporate non-use values and locals’ prioritization of ES uses. We gradually extend the bioeconomic model to involve the commercial fishing benefits, recreational fishing benefits, non-use benefits, and prioritization weights attached to these by the local population for optimizing the coastal cod biomass. Overall, the bioeconomic dynamic optimization results suggest that disregarding the non-use benefits attached to coastal cod results in the undervaluation of stock, which can lead to significant overexploitation and degradation.

The research presented in this thesis has focused on the economic valuation of climate change impacts on ecotourism in a coastal wetland using three different methods of stated-preference techniques to provide answers to different research questions related to coastal tourism and climate change. Rekawa coastal wetland in Southern Sri Lanka was taken as the empirical context to examine the identified research questions. The first issue studied in this thesis concerns the balance between conservation goals and the development of ecotourism in coastal wetland management. Our findings provide empirical evidence suggesting that ecotourism is not only an economically viable industry but also a good ecological policy instrument. This since economic benefits arising from ecotourism can be used for environmental protection and biodiversity conservation by ensuring habitat protection for a broad set of species. We have proved that well-managed sustainable tourism in and around coastal wetlands can bring important economic and ecological benefits. The second research question attempts to provide a regional perspective on intended future visitation behavior of both domestic and foreign tourists to a coastal wetland under climate change impacts explained by a climate change induced environmental index based on IPCC scenarios. The climate change induced environmental index that we developed, was found to be a significant determinant of intended visitation behavior of tourists. The final part of the research refers to tourists’ preferences and willingness to pay for restoration of mangroves to reduce the climate change impacts on ecotourism. Our findings highlight the importance of mangrove protection as an adaptation strategy to minimize the climate change impacts. Tourists’ preferences and willingness to pay for mangrove protection support the formation of an environmental protection fund and use of it in different mangrove protection measures. If increasing impacts of climate change are unattended in a timely fashion with site-specific adaptation measures, future ecotourism in coastal wetlands could be at risk.

This thesis is published on Munin with a CC BY license. Cuscuta is a genus of parasitic plants that form cross-species bridges and connect to the xylem and phloem of a wide variety of host plants. Because of their unique lifestyle, research into processes like the formation of connections in between plant cells and plant immunity would benefit from Cuscuta as a model system. However, a method to study gene functions in a Cuscuta species is still missing. Its development was therefore chosen as the goal of this thesis. In vitro culture techniques for Cuscuta campestris were developed and Agrobacterium transformation of Cuscuta tissue was successfully performed in two different systems, the adhesive disk area close to the parasitic infection organ, and seedlings of C. campestris. As an alternative method for gene function studies in Cuscuta, virus induced gene silencing was tested in C. campestris. Mineral transport across the host-parasite border was studied and the potential use of interspecies plasmodesmata between Cuscuta and its hosts was investigated. The results presented in this thesis allow for first gene function studies in Cuscuta and are good foundations for the development of pipelines for transgenic plant production and gene silencing techniques. Challenges and opportunities with this system are outlined. The conclusions of this thesis will help to “tame” Cuscuta and use its unique physique and strategies for host plant infection to establish a model species for studying plant-cell connections, transport processes and plant immunity.

Infectious diseases have been a problem for humans since the beginning of human existence. The “golden age” of antibiotics started at the end of the 1920s, with the discovery of penicillin by Sir Alexander Fleming. This was followed by the discovery of several life-saving antibiotics. The number of new marketed antibiotics has declined, and most pharmaceutical companies are no longer working in antibiotic development. This in itself would be unproblematic, had it not been for the rapid ability of bacteria to become resistant towards previously debilitating agents. The need for new antibiotics is therefore eminent. Natural products have been important contributors for antibiotic drug discovery and development. Microorganisms have been a particularly proliferative source of antibiotics, providing us with among others the penicillins, aminoglycosides, tetracyclines and polymyxins. Most naturally derived pharmaceuticals, including antibiotics, originate from terrestrial organisms. This is mainly because the terrestrial environment historically has been easier to access compared to the marine environment below the intertidal zone. The marine environment is highly diverse, and there is still a huge biodiversity that is yet to be explored. In this project, Arctic and sub-Arctic marine bacteria and fungi were cultivated and studied for their production of natural products. The cultures were extracted and fractionated, and the fractions were tested for bioactivity, mainly focusing on antibacterial activity. Using bioactivity-guided isolation, compounds were isolated and structurally characterized. Finally, the bioactivity of the isolated compounds was broadly evaluated. In paper I, a known siderophore, serratiochelin A, was isolated from a co-culture of two bacteria, Serratia sp. and Shewanella sp. The compound was not detected in axenic cultures, indicating that cocultivation triggered production. The acid-catalyzed degradation of serratiochelin A into serratiochelin C was also observed. Serratiochelin A had weak activity against Staphylococcus aureus, melanoma cells and non-malignant lung fibroblasts. No activity was observed for the degradation product serratiochelin C, indicating that the oxazoline moiety in the original compound is essential for the bioactivity. In paper II, a marine bacterium Lacinutrix sp. was cultivated and studied for its ability to produce bioactive natural products. Through bioactivity-guided isolation, two new lyso-ornithine lipids were isolated, and their structures elucidated, showing that they only differed by the length of the hydrocarbon tail. Analysis by UHPLC-HR-MS indicate that the purified solutions are mixtures of isomers, but these were not possible to separate by preparative HPLC-MS. The compounds were evaluated for antibacterial activity and antiproliferative activity against human cells. Compound 1 displayed weak activity against Streptococcus agalactiae, while compound 2 had weak activity against melanoma cells. In paper III, a new dimeric naphthopyrone substituted with a sulphate group was isolated in high yields from cultures of an obligate marine fungus in the family Lulworthiaceae. The compound was tested against an extended panel of clinical bacterial isolates and showed potent antibacterial activity against several clinical methicillin-resistant Staphylococcus aureus isolates, with MICs down to 1.56 μg/mL. Acid-catalyzed degradation was also observed. The compound also displayed moderate activities against three human cell lines: melanoma, hepatocellular carcinoma, and non-malignant lung fibroblast. In paper IV, a new chlovalicin variant, chlovalicin B, was isolated from cultures of the obligate marine fungus Digitatispora marina. The fungus has previously been studied for its distribution in the marine environment but has not been extensively studied for its biosynthetic potential. The compound was isolated in low yields, and the structure was elucidated by NMR and HRMS experiments. The compound was assessed for a range of bioactivities and had weak antiproliferative activity against human melanoma cells.

Marine ecosystems are under pressures of human activities that have altered their dynamics and structure during the last five decades, but there can also vary due to internal dynamics or chance. Managers focus on human activities and often ignore the contribution of internal dynamics and chance to ecosystem dynamics in the decision-making process. In this thesis, I use food-web modelling based on the principles of Chance and Necessity to explore the possible variability of the Nordic Seas’ food-web. I show that internal dynamics and randomness have a key role in the variability of marine food-webs. I also show that climate change and fisheries affect the variability of the Nordic Seas in a combined manner, which suggest that both stressors should not be considered separately for management. I suggest that Chance and Necessity can used a tool to inform adaptive management, ecosystem-based management, and integrated ecosystem assessment.

This thesis addressed phenotypic and genetic variation in seasonal time keeping mechanisms of the tundra vole (Microtus oeconomus) and the common vole (Microtus arvalis). Voles (Microtus) are short-lived, non-hibernating and seasonally breeding rodents. The genus has rapidly evolved (< 2 million years) into one of the most speciose mammalian genera (Sitnikova et al. 2007; Triant and DeWoody 2006) and occupies a wide range of latitudes (14-78°N) with the tundra vole being the most wide spread species. Seasonality is strong at high latitudes with lower and more seasonally fluctuating ambient temperatures (Hut et al. 2013). Therefore, animals have evolved mechanisms to time their life cycles with the strongly cyclical environment. The annual day length cycle is the most reliable cue to predict upcoming changes and prepare accordingly. This information is integrated by the photoneuroendocrine system (PNES) that coordinates phenotypic changes such as seasonal molt and reproduction (D. Hazlerigg and Simonneaux 2015). In paper I, we showed that under laboratory conditions, short winter photoperiods alone reduced somatic growth (body mass) in tundra voles and gonadal growth (reproduction) in common voles. Since both vole species were caught at the same location (the Netherlands, 53°N), the different response can be ascribed to genetic variation between the species. This was possibly shaped by different selection pressures occurring during the more northern (tundra vole) and southern (common vole) paleogeographic history of the two species. Within and among vole species, the timing of breeding shows great year-to-year variation (Tast 1966; T. Ergon et al. 2001), which is apparently influenced by environmental conditions such as ambient temperature (Kriegsfeld, Trasy, and Nelson 2000). The breeding season starts in spring with the overwintering individuals producing the first spring-born cohort of pups. The short gestation and development times allow these spring-born cohorts to reproduce during the same breeding season as their parents and produce several subsequent cohorts until the end of the breeding season in autumn (Horton 1984a; Gliwicz 1996). In papers II and III, we investigated the critical photoperiod thresholds for initiation of accelerated reproductive maturation in voles on a spring developmental program and for the deceleration of development in voles on an autumn program. Further, we assessed the influence of ambient temperature (10°C or 21°C) on the response parameters. Seasonal gene expression, hormone levels, downstream body-mass and gonadal mass had different species-specific response thresholds to photoperiod and temperature. This indicates that the system has a hierarchical organization that allowed for independent modulation at various levels. The results of these experiments also emphasise the importance of the direction of day length change in setting maturation trajectories. In Paper IV we searched for signatures of selection across the genomes of tundra voles from a northern (70°N) and southern (53°N) population. A signature of selection is a reduction in population diversity at a certain genomic position because of positive selection on a favoured allele. We found selection on a paralogue of the Aldh1a1 gene located between the Aldh1a1 and Aldh1a7 genes. We found two additional Aldh1a1-like paralogues on the same locus. Other voles investigated also had two or three paralogues, which are not present in mouse and rat genomes. Aldh1a1 has a central role in photoperiodic retinoic acid signaling in the rodent hypothalamus, which may be involved in seasonal body mass regulation (Helfer, Barrett, and Morgan 2019; Shearer, Stoney, Nanescu, et al. 2012). Aldh1a7 is also considered as a paralogue of Aldh1a1 (90% amino acid sequence homology in the mouse) but it is not involved in retinoic acid signaling (Hsu et al. 1999). The paralogues found in the vole had the highest sequence homology with Aldh1a7. Future research has to clarify the function of this gene and whether this selection pressure is associated with latitude. Taken together we found various levels of flexibility within the vole PNES where ambient temperature and photoperiodic history can modulate the seasonal response which is possibly affected by evolution at different latitudes. Reproductive opportunism and an ability to override photoperiodic information may be favoured in voles living at higher latitudes which may lead to genetic differences between and within species.

Population cycles in small rodents have attracted attention from ecologists for more than a century. This spectacular phenomenon is crucial for the functioning of many northern food-webs and has intrigued ecologist because of its lessons for general ecology. Knowledge about the rodent cycle has, however, been hampered by the lack of reliable monitoring methods both for rodents and some of their assumed interactants (e.g. the small mustelids). In resent decades, camera traps have become widely used in ecology as they provide a cost-efficient and non-invasive method for wildlife monitoring. In this thesis, consisting of four studies, I will investigate how camera trap tunnels tailored for small mammals can enhance rodent monitoring. First, in study I, I together with colleagues conducted the first large scale assessment of the applicability of tunnel-based camera traps to estimate population parameters in a small mammal community, including during a long Arctic winter. We showed that the camera trap provide estimates of rodent occupancy also under the snow during winter. Further we give recommendation on micro-scale placement of the traps to maximize technical functionality in order to avoid loss of data. Then, in study II, we expand on dynamic occupancy models for interacting species by including two nested spatial scales. This allows for camera trap-based investigation of the rodent-mustelid interaction on both a local and a landscape scale. Features of this interaction are assumed to be a key to understand the cause(s) of the rodent population cycles. In study III, we apply the statistical framework developed in study II to a dataset derived from the long-term monitoring program Climate-ecological Observatory for Arctic Tundra (COAT). Our results show that presence of mustelids increased the extinction probability of rodents on both a local and a landscape scale. Furthermore, we demonstrate a clear habitat dependence and indications of a season-dependency in the rodent-mustelid interaction strength. Finally, in study IV, we assess whether camera trap-based abundance indices can be used to study population dynamics of two rodent species (gray-sided vole (Myodes rufocanus) and tundra vole (Microtus oeconomus)). This was done by comparing camera trap-based abundance indices to abundance estimated from capture-mark-recapture (CMR). For gray-sided voles a single camera trap provided reliable abundance indices with camera trap counts aggregated over 5-days. For tundra voles counts from four spatially replicated camera traps from a single day within the same local population needed to be aggregated to obtain a good correspondence to the abundance estimated from CMR. Such species-differences imply that the design of camera trap studies should be adapted to the species in focus. This study further highlight that camera traps yield much more temporally resolved abundance metrics than alternative methods. To conclude, the work presented in this thesis demonstrates how camera trap-based rodent monitoring provides multiple improvements compared to previous methods. Camera traps are non-invasive avoiding the ethical issues kill-trapping are fraught with. Further, camera traps provide data year round - including from under the snow- on a fine temporal scale. In addition camera traps are not species specific and provide data on the whole small mammals community including small rodents, shrews and small mustelids. In addition, camera traps provide a reliable abundance index at least for two of the most ecologically important rodents species in northern Fennoscandia. Furthermore, this thesis present a statistical framework for investigating mustelid-rodent interactions based camera trap data and exemplify how this framework can improve on the knowledge on one of the longest standing mysteries in ecology.

This thesis presents a study of the impact of climate warming on deep demersal fish communities East of Greenland, in a transition zone between Atlantic and Arctic waters. Climate change was expected to affect fish community composition and functional characterization via poleward distributional shifts and changes in abundance. To assess the climate driven effects on fish communities, I used long term survey data (1998 – 2016) covering a depth range of nearly 1500m. Data on taxonomic composition and abundance were combined with functional traits information to address temporal changes in diversity, community structure and functional characterization at different depths. The rapid warming registered during the study period was associated with a decline in both taxonomic and functional diversity, with the sharpest negative trends at depths between 300 and 1000m. Overall, the abundance of boreal species with a generalist diet, like greater argentine (Argentina silus) and Tusk (Brosme brosme) increased, whereas the abundance of Arctic fish benthivores like Lycodes spp. and northern wolffish (Anarhichas denticulatus) decreased. Functional reorganization was most pronounced at depths from 300 to 750m. Species living at great depths down to 1000m were affected by climate events detected at the surface, displaying rapid responses that were likely mediated by behaviour. These findings suggest that deep sea demersal species can respond just as fast to environmental change as species living in the shallower waters of shelf seas. The diversity loss was not consistent with the general expectations of a climate driven increase in Arctic marine biodiversity, observed in other high latitude ecosystems. Clearly, regional conditions may decide the climate driven effects on diversity, as the combination of currents and topography East of Greenland seems to inhibit colonization by boreal species. The documented taxonomic and functional reorganization of the fish communities east of Greenland are likely to affect ecosystem functioning and vulnerability. The increasing importance of generalist species, also feeding in the pelagic food web compartment, changes the main pathways of energy and material flow, and tends to connect more tightly the food web. The increased connectivity of the food web may promote the spread of perturbations within an ecosystem that is losing adaptive capacity due to a decline in diversity. Since the East Greenland Ecosystem seems to be highly vulnerable to environmental change, future monitoring and a precautionary approach to fisheries and ecosystem management is suggested.

Long-term temperature increases, higher frequencies of extreme weather events and changes in food web structures will all affect the state of Arctic tundra ecosystems at different temporal and spatial scales. Ecologists are tasked with understanding these biotic and abiotic interactions and finding methods to measure them. This thesis applies new technology and methods within the principles of adaptive monitoring to achieve four overarching goals: 1) Design a conceptual model for Svalbard’s moss tundra ecosystem and define the vegetation monitoring needs of high Arctic tundra systems in the context of climate change and herbivore management. 2) Design new monitoring approaches that help quantify habitat types and drivers of future vegetation state changes. 3) Evaluate the practical implications of using drone imagery, photogrammetry, and image classification-based approaches for monitoring. 4) Assess how the findings of the thesis can contribute to future adaptive monitoring of moss tundra. Drone images and random forest classifiers were reliably able to distinguish up to 15 different tundra ground cover classes, including those that represent disturbances such as winter damage from extreme weather events, pink-footed goose grubbing and bare ground. Snowmelt progression was mapped using drone and satellite images and combined with telemetry data to enable analysis of pink-footed goose behavior. This revealed a consistent correspondence, driven by vegetation class and snowmelt date, of habitat use and vegetation disturbance across spatial scales. Collecting ground truthing data in the field requires a good understanding of focal ecosystem components and their interactions with both abiotic and biotic factors, to not only detect visually distinctive, but also ecologically relevant ground cover classes. A close integration of detailed field-based assessments and drone images can elevate studies of causal ecological relationships into a spatial context. In addition, drone images will continue to improve the quality of information gained from satellite-based remote sensing.

The European Arctic is characterized by large surface areas of coastal seas and long coastlines where important ecosystem processes are regulated by marine microbiomes that contribute to global carbon cycling via primary productivity and atmospheric CO2 drawdown. In addition to biogeochemical cycling, these complex microbial ecosystems also support major marine food webs and lend themselves to marine bioprospecting for novel biotechnologies. However, they are not well understood and remain unpredictable. For example, northern coastal Norway is periodically affected by unwanted ecosystem functions such as sporadic harmful algae blooms that are detrimental to local aquaculture industry. These cold adapted marine microbiomes perform ecological processes that are often driven by phytoplankton and their associated heterotrophic communities which undergo strong seasonal variation within complex and variable oceanographical and biogeochemical conditions. Climate change driven temperature increases with resulting direct and undirect changes on environmental conditions have been reported to alter microbial community structures of surface microbiomes. Hence, these important microbial ecosystems are in transition, and it is difficult to predict the trajectory of how specific ecosystem functions may be changing. This thesis is centered around cold-water communities of phytoplankton and bacterioplankton with the aim to enhance our contemporary understanding on surface microbial ecosystems and their function with respect to carbon cycling, community dynamics and community selection. Paper I and Paper II took place in northern Norwegian fjords and costal systems where spatial variation and magnitude of atmospheric CO2 uptake were investigated and the main physical and biological factors driving surface partial pressure of CO2 with respect to atmospheric CO2 were assessed in four fjords and a coastal bay through seasonal changes. The results indicate that northern Norwegian fjords free of sea-ice act as a sink for atmospheric CO2, although the magnitude of air-to-sea CO2 flux showed fjord-specific variation, and the biological fixation of CO2 is a strong driver of CO2 undersaturation. In addition, the temporal and spatial dynamics of early summer microeukaryotes with co-blooming bacteria were examined during a destructive haptophyte Chrysochromulina leadbeateri-associated harmful algae bloom. The coastal habitats harbor highly localized phytoplankton microbial communities which succession dynamics of blooming populations (including C. leadbeateri) undergo strong temporal variability. Paper III took place across a long transect from Atlantic water influenced Barents Sea to less influenced Nansen Basin in the high Arctic with the aim to understand more about the influence of ecological community processes on the distribution of phytoplankton and microbial taxa. Inferences based on phylogenetic turnover, generated through null modeling randomization of phylogenetic relatedness, indicates that the dominant selective force is homogeneous across the studied transect despite differences regarding temperature, sea-ice conditions, and origin of a water mass. Our findings highlight that both large scale and local studies are important to form the needed comprehensive understanding of these microbial ecosystems as the regional taxonomic pool is determined by fundamental ecological processes but community structure influencing ecosystem function is instead subjected to more localized variation of abiotic and biotic factors.

Climate warming in the Arctic has resulted in widespread changes in the physical oceanographic characteristics of the Arctic Ocean. One particularly visible change is the loss of sea ice both within the Arctic Ocean and in the surrounding shelf seas. Compared to the other shelf seas, the Barents Sea has experienced the largest declines in sea ice extent, with much of this loss occurring during winter. In response to these changes, a range of biological responses have already begun–from population declines to changes in community compositions. This thesis explored sea ice dependencies of various Arctic marine organisms. Paper 1 explored if a pelagic phase could be party of the life cycle of a so-far presumed fully sea ice-associated amphipod. Paper 2 investigated seasonal (rarely studied polar night versus commonly studied polar day) diet changes in three zooplankton and two sea ice-associated amphipod species. Paper 3 quantified the contributions of sea ice-associated and pelagic (open water) carbon sources to diets of two different Arctic seal species: the harp and ringed seals. The main findings of this thesis demonstrate that in this time of transition–where Arctic sea ice is still present but receding–the studied Arctic marine organisms exhibit a wide range of sea ice dependence. While the seal species displayed strong seasonal associations to the sea ice habitat (in terms of energetic sources), zooplankton and sea ice amphipod species had varying degrees of trophic plasticity (for example, polar night feeding activity and being supported by pelagic carbon). This thesis research increases the knowledge of potential biological response to the current state of the Arctic.

The focus of this thesis is on the economic performance and technical efficiency of a Vietnamese fishing fleet by the use of data envelopment analysis (DEA). The double bootstrap method has been used to overcome some of the limitations of DEA. In addition, the dissertation evaluates fishers’ perceptions of negative events affecting the fishing activities. The first of three papers presents the investigated fleet and the economic performance in 2016 under open access conditions. Fixed and variable costs, and revenue have been used for estimating the technical efficiency. By adopting double bootstrap DEA under the hypothesis of variable returns to scale, the average technical efficiency of the fleet is found to be relatively high. Nevertheless, the DEA calculations showed that the current catch level could be obtained by a fishing effort 24–35% lower than the actual vessel activity. Vessel size and fishing experience are all factors affecting the technical efficiency. The second paper measures and compares the technical efficiency using physical vs. economic measures. The study focuses on the same 52 Nha Trang purse seiners as in the first paper. Adopting the double bootstrap DEA method, the findings show that economic measures give a lower level of technical efficiency than that which is obtained by physical measures. However, there is significant difference in the technical efficiency between these two measures. The skipper’s experience and interest payment significantly affects the physically based technical efficiency at the 5% level. This study concludes that physical variables, which are often more accessible, are capable of capturing essential economic differences between vessels. The third paper studies the same purse seine fishers’ perceptions of how environmental and socio-economic factors influence their life and fishing activities. The findings are that storms/cyclones, severe floods, heavy rains, high temperature, big waves and bad weather reduce fish density, and the poor availability of capital, health conditions and crew access all negatively affect fishing activities. The fishers’ perceptions of the increased temperature and declining fish stocks over time are in line with available data, whereas their perceptions of the frequencies of storms, floods and heavy rains differ from the observations. Despite increasing frequencies of storms and precipitation not actually observed, the fishers perceive such factors as creating problems for their current fishing activities. Almost all the fishers in the sample expected the frequency and severity of rainfalls and the average temperature to increase in the future, while fish stock availability will decline. However, climate change is not expected to be among the most important negative factors in the future. Cost of fishing, health conditions, efficient fishing gear and boats, as well as the resource situation, represent important factors causing greater concern among fishers regarding future fishing activities.

We took an experimental approach to study what may contribute to such behavior, and what effect these choices have on individual wellbeing. We used three independent surveys to analyze this, all three measuring positional preferences in a broad spectrum of domains. If left uncorrected, there might be large unintended external effects from positional preferences, which is why this research is necessary. On a greater scale, we can use this understanding as a tool to design a policy instrument correcting for the suboptimal behavior when people are concerned with relative performance. Our first study focused on the effect of gender, closeness, and relevance of the reference group (with whom we compare) on positional preferences and we explored how social identification in the relevant domains contributes to such behavior. The focus of our second study was to test if the instruments commonly used in this research are robust to a variation in levels (endowment) or subject (deciding for the self or deciding for a grandchild). Finally, our third study focused on the effects of positional preferences on life satisfaction. To test our hypotheses we ran a set of logistic regressions, controlling for a variety of social-demographic indicators. Our findings suggest that comparing with an average in society elicits a higher share of positional preferences than comparing with someone close and relevant, and we found that social identification with a domain correlates with positional preferences in the same domain. We also found that gender of the individual, and the reference group matter for positional preferences in some domains, but not all domains are gendered. When we tested the robustness of these instruments, we found that they are relatively insensitive to a variation in levels and in the targeted subject, which is reassuring as it validates earlier findings and makes them replicable. Finally, our third study suggests that positionality in all the included domains has negative and significant effects on how we feel about ourselves.

Thinking of fisheries as a system is a relatively new approach in fisheries science and management. As part of my contribution to this perspective, this thesis uses mental models as a new approach to gain insights into how individuals conceptualize fisheries. Mental models are internal representations of the surrounding world (e.g., phenomena, processes, problems) and they are important because these representations shape how individuals solve problems, take decisions, and communicate. Following an established methodology for analyzing mental models, this thesis begins with establishing a reference model of fishery systems. This reference model is then compared with: 1) the conceptualization extracted from 18 definitions of fisheries formulated by various organizations involved in fisheries management and reference materials; 2) the conceptualization extracted from South African learning material (textbooks used in Grade 9, last compulsory grade, and textbooks used in the only BSc with a major in fisheries offered in the country). The analysis indicates that neither the definitions nor the textbooks manage to provide a comprehensive and balanced understanding of fisheries as systems. Shifting the focus from artefacts (i.e., definitions, textbooks) to human subjects, this thesis developed and tested a novel instrument for eliciting mental models about fisheries. This instrument can be used to elicit the mental models that various stakeholders have about fisheries and the analysis of these representations can guide targeted raising awareness efforts so that gaps or misunderstandings are addressed. The mental models elicited through the three studies are then compared. This thesis introduces the mental models approach as a new method that has the potential to push research further on the path of conceptualizing fishery as a system from a holistic approach.

Climate change driven increases in temperature are enhancing land-ocean connectivity in the coastal Arctic, with a range of implications for coastal food-webs and contaminant cycling. Terrestrial inputs are a direct source of carbon and legacy contaminants to coastal areas, but as a source of freshwater, nutrients and suspended inorganic sediments, they can also affect coastal food-webs and contaminant cycling indirectly through impacts on phytoplankton community structure and contaminant removal and burial. To investigate coastal responses to terrestrial inputs, we conducted a field study in a river- and glacier- influenced Arctic fjord system (Isfjorden, Svalbard), in May, June and August, 2018 with a follow-up study in 2019. Environmental data, zooplankton and benthos were collected from 17 fjord stations along transects from river estuaries and glacier fronts to the outer fjord. Fauna were analyzed for persistent organic pollutants and dietary carbon sources were assessed using a variety of biogeochemical tracer techniques, including fatty acid trophic markers and bulk stable isotopes. Our observations revealed a pervasive freshwater footprint in the inner fjord arms, the geochemical properties of which varied spatially and seasonally as the melt season progressed from snowmelt in June to glacial melt and permafrost runoff in August. Zooplankton fatty acid profiles were strongly coupled to fatty acid profiles of water column particulate organic matter, reflecting seasonal and spatial shifts in phytoplankton community structure, with elevated contributions of diatom fatty acids in May following the spring phytoplankton bloom, to dinoflagellate and terrestrial fatty acids in June and August when high sediment loads attenuate light in the nearshore. Persistent organic pollutant concentrations in coastal fauna were inversely related to terrestrial inputs spatially and seasonally, suggesting that freshwater and associated high rates of inorganic sedimentation act to dilute, bind and bury persistent organic pollutants in the inner fjord arms of Isfjorden. Our results highlight the physical, chemical and biological impact of terrestrial inputs on downstream coastal ecosystems in a rapidly changing Arctic environment.

Understanding Arctic deep-sea ecosystem structure and functioning is an urgent task because ongoing sea-ice reduction modifies and opens up these regions for resource exploitation. This thesis aims to increase knowledge on epibenthos in the Chukchi Borderland (deep Arctic Ocean). Paper I documents low epifaunal densities and biomass, a total of 152 taxa, and dominance of Echinodermata, Arthropoda and Cnidaria for taxon richness and/or abundance/biomass. Most taxa had Atlantic biogeographic affinity. Ridge and plateau community structure did not differ but western and eastern communities did, linked to food input and drop-stone availability. Paper II findings generally support the current view of common trait modalities in deep-sea epibenthos. Higher functional diversity at mid-depth than deep stations indicated more variable resource use, while higher functional redundancy in basin communities suggested adaptation to more homogeneous environments by fewer, shared traits. Paper III suggests tighter pelagic-benthic coupling in 2005 (high sea-ice cover) than 2016 (low sea-ice cover), reflected in higher isotopic-niche overlap and shorter isotopic-distances between pelagic and benthic systems in 2005. Isotope values suggest higher ice algal contribution in 2005 and more refractory food consumed by benthos in 2016. This study adds much-needed biological and ecological knowledge with implications for vulnerability and resilience and highlights the need for deep-sea monitoring.

Consumers’ perception of seafood products plays a critical role in determining their consumption behaviour. As a great quantity of seafood is produced by aquaculture, specifically farmed fish, consumers’ perception of farmed fish is crucial. In recent years, consumers in developing and emerging countries have increased their concern about seafood safety. This thesis investigates consumers’ perception of seafood in an emerging market such as Bangladesh and their willingness to pay (WTP) for fish attributes such as safety and green labels. The thesis contributes to the literature by adding value to the empirical knowledge of consumers’ perceptions and attitudes and the discrepancy of knowledge in emerging markets, especially about sustainable and organic farmed fish. The thesis comprises an independent introductory section and four individual papers.

The dissertation includes four papers altogether. Three papers examine mechanisms for price transmission between markets. Among them, one deals with price transmission along the supply chain, and the other two deal with price transmission across spatially distinct markets. The fourth paper measures the effects of demand shifts on the market price equilibrium. Paper 1 investigates price transmission relationships in the salmon value chain between the export market of Norway and retail markets of France and Spain. We assume processing costs have a significant impact on a vertical price linkage along the supply chain. Specifically, asymmetric price transmission is investigated along the supply chain of two salmon products, a relatively unprocessed product (fresh salmon) and a more processed product (smoked salmon). The threshold cointegration and the asymmetric error correction models are estimated to examine the patterns of price adjustment. Results indicate a price transmission relationship in both markets along the fresh salmon supply chain but not along the smoked salmon chain in either market. Furthermore, for the fresh salmon supply chain, asymmetric adjustment is observed in both markets. Processing salmon into value-added consumer products involves additional inputs, including labor, capital, marketing, and packaging costs and time. The greater the share of these non-raw materials costs in the final consumer prices, the less the price influence of farmed fish on the final product price. Hence, we can argue that price transmission between the export and retail salmon markets decreases as more processing is involved. The second paper explores market integration and spatial price transmission in the regional grain markets in Ethiopia. Since mid-2006, prices of basic food crops (such as wheat and maize) have persistently increased and have become a critical challenge in Ethiopia. The literature indicates that food prices in any market may change as a result of several factors, including price shock diffusion from international markets (Baquedano & Liefert, 2014; Ceballos et al., 2017), changes in the exchange rate (Hazel et al., 1990; Dawe, 2008), changes in domestic demand and supply conditions (Brækkan et al., 2018), and in the market structure (Abdulai, 2000). In this paper, the objective was to investigate whether the Ethiopian grain market structure has contributed to price increases in the Ethiopian grain market. The study uses monthly wholesale prices of wheat, maize, and teff from major regional grain markets in Ethiopia. The Engle-Granger and threshold cointegration models were the main methods employed to investigate the extent, speed, and nature of price signal transmission between the central and major regional grain markets. The estimated results given by both models suggest the presence of long-run relationships between the central and major regional grain markets for each commodity. Moreover, the results obtained from the threshold cointegration model indicate the general absence of asymmetric price adjustment in each of the markets. This might imply the presence of efficient price transmission in the Ethiopian grain market. Hence, I argue that this study provides insufficient evidence to support the hypothesis that the price adjustment behavior of grain traders (or market structure) leads to sustained grain-price increases in Ethiopia. The third paper investigate price transmission in EU pork markets. The pork market in the EU has undergone important changes in recent years, such as the growing concentration of power in both producing and consuming countries, which might impact the price transmission process between markets. This study therefore investigated price transmission between major EU spatial pork markets. Two different techniques, namely threshold autoregressive and local polynomial techniques, were applied to obtain reliable results. The results suggest that price transmission mechanisms vary significantly between different EU markets. However, the transmission speeds between the markets are overall small, indicating that price adjustments take a long time in each market. Furthermore, the estimated results provide some evidence of asymmetric adjustment within the EU pork markets. The fourth paper takes a different approach by studying market price formation. Growing global demand for seafood has shifted the demand curves in the world seafood markets upward. In this paper, we use the demand index approach of Marsh (2003) to measure the growth in seafood demand of 107 countries between 1984 and 2013. The estimated results are then used to calculate aggregate demand growth by income level, regionally, and over time. Results indicate that demand growth varies considerably across countries, regions, income groups, and over time. Furthermore, while the literature show seafood production has more than doubled since the mid-1980s, our results indicate that global demand for seafood has exceeded the global seafood supply, which explains the increasing global seafood prices.

The manuscripts of the dissertation presented here encompass several aspects of adaptations in ice-associated amphipods, focussing mainly on their ability to cope with increased light levels, including the ultraviolet radiation (UVR), under thinner or more dispersed sea ice. A decrease in multi-year ice (MYI) in the Arctic, and a concurrent reduction in stable habitat for ice-associated species, is a substantial threat to the ecosystem in the Arctic Ocean, as these amphipods act as a key trophic link between primary production inside and under sea ice, and higher trophic levels. In a shift from thicker multi-year ice to thinner and less coherent first-year ice, the changes in under-ice light levels may be considered as the second-most significant factor, after the loss of the habitat itself. This thesis has as its overarching ambition to contribute to our understanding of how this change may affect the organisms living in association with the Arctic sea ice. While the reduction in stratospheric ozone and the resulting seasonal increases in ultraviolet radiation (UVR) have been halted and to some extent reversed, the recovery period is calculated to be protracted, and might even be affected negatively by the ongoing warming of the troposphere through the ongoing emission of greenhouse gases. So both the direct and indirect effects of UVR on sea ice-associated amphipods have been proven to be a significant factor, especially in the context of a reduction in both thickness and extent of the Arctic sea ice cover. The effects of pigment ingestion and accumulation have also been of particular interest, as well as the capacity of organisms to cope with and adapt to elevated, radiation-induced oxidative stress. Another aspect of this thesis has been to investigate hitherto and potentially overlooked aspects of the distribution and occurrence of ice-associated amphipods in the Antarctic. This study contributed to altering the previously held assumption that ice-associated amphipods in Antarctic waters were predominantly originating from the shallow benthos and were thus able to interact with sea ice only when it is over relatively shallow depths. One of the papers presented in this thesis documents several pelagic amphipod species living in close association with sea ice. Hence, an important conclusion from this is that there is a pelago-sympagic component of Antarctic amphipods in the Weddell Sea.